What is the fastest production dirt bike ever made?

The 2008 Husqvarna TC 450. Below is an excerpt from a motorcycle-usa.com article testing the bike. “A few months ago a European publication claimed that Husky’s TC 450 has six more horsepower than any other 450 in the field. When I read that article my mind was full of doubts… Until now. This bike is hands down the fastest stock 450 I have ever ridden, and I have thrown my leg over heaps of motorcycles. It feels like a bored-out 450 that has a secret turbo charger under the tank.”